Circolo Popolare, or Circolo for short, will be inspired by the Sicilian coast and open in a 280-cover, 9,000 sq ft site in Rathbone Square, including a 60-cover outdoor terrace.
The restaurant will offer a "slightly over the top menu" of small plates and larger sharing platters including metre-long pizzas loaded with San Marzano tomato and burrata from Puglia; and centrepieces from the Sicilian grill, such as calamari e lemoni and pork skewers al arrabiata.
Desserts will include the group's Instagram hit lemon meringue pie as well as a 1l ice-cream sundae served with giant cookie chunks.
More than 20,000 bottles of spirits will line the walls of the plant-filled restaurant, while thousands of festoon lights will adorn the ceiling.
The Big Mamma group opened Gloria in east London earlier this year and has seven trattorias as well as a 50,000 sq ft food market in France.